Gwent's Police and Crime Commissioner and Gwent Police's former chief constable will appear before the Home Affairs Select Committee in London later.
Both parties will give their side of events that led to Mrs Napier's departure at the meeting in Westminister this afternoon.
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Soldiers from 1st Battalion Welsh Guards have overseen the planting of 2,000 oak trees to mark the centenary of the Battle of the Somme.
Wales meet Belgium in a Euro 2016 quarter-final in Lille on Friday night.
Gareth Bale insists reaching the last eight of Euro 2016 is not enough for Wales ahead of their quarter-final against Belgium.